2022-04-07 20:20:50

by Xiaoke Wang

Subject: [PATCH v2] drm/msm/mdp5: check the return of kzalloc()

From: Xiaoke Wang <[email protected]>

kzalloc() is a memory allocation function which can return NULL when
some internal memory errors happen. So it is better to check it to
prevent potential wrong memory access.

Besides, since mdp5_plane_reset() is void type, so we should better
set `plane-state` to NULL after releasing it.

Signed-off-by: Xiaoke Wang <[email protected]>
---
ChangeLog:
v1->v2 simplify the patch and update the description.
drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c b/drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c
index c6b69af..50e8542 100644
--- a/drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c
+++ b/drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c
@@ -90,7 +90,10 @@ static void mdp5_plane_reset(struct drm_plane *plane)
__drm_atomic_helper_plane_destroy_state(plane->state);

kfree(to_mdp5_plane_state(plane->state));
+ plane->state = NULL;
mdp5_state = kzalloc(sizeof(*mdp5_state), GFP_KERNEL);
+ if (!mdp5_state)
+ return;

if (plane->type == DRM_PLANE_TYPE_PRIMARY)
mdp5_state->base.zpos = STAGE_BASE;
--

2022-04-09 00:19:29

by Dmitry Baryshkov

Subject: Re: [PATCH v2] drm/msm/mdp5: check the return of kzalloc()

On Thu, 7 Apr 2022 at 05:33, <[email protected]> wrote:
>
> From: Xiaoke Wang <[email protected]>
>
> kzalloc() is a memory allocation function which can return NULL when
> some internal memory errors happen. So it is better to check it to
> prevent potential wrong memory access.
>
> Besides, since mdp5_plane_reset() is void type, so we should better
> set `plane-state` to NULL after releasing it.
>
> Signed-off-by: Xiaoke Wang <[email protected]>

Reviewed-by: Dmitry Baryshkov <[email protected]>

> ---
> ChangeLog:
> v1->v2 simplify the patch and update the description.
> drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c b/drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c
> index c6b69af..50e8542 100644
> --- a/drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c
> +++ b/drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c
> @@ -90,7 +90,10 @@ static void mdp5_plane_reset(struct drm_plane *plane)
> __drm_atomic_helper_plane_destroy_state(plane->state);
>
> kfree(to_mdp5_plane_state(plane->state));
> + plane->state = NULL;
> mdp5_state = kzalloc(sizeof(*mdp5_state), GFP_KERNEL);
> + if (!mdp5_state)
> + return;
>
> if (plane->type == DRM_PLANE_TYPE_PRIMARY)
> mdp5_state->base.zpos = STAGE_BASE;
> --



--
With best wishes
Dmitry